The TV out signal shares the pin with the microphone input. The phone tells the difference and switches accordingly based on the impedance on that pin. So there is a remote possibility, although not very likely, that a very weird headset or dodgy adapter may be detected wrongly and get the video signal pushed to the microphone, but that should not result in strange noises in the headphone speakers. It is more likely that your adapter is just plain wrong. What you describe sounds like a grounding issue. Possibly the mic and gnd pins swapped around.